security-admin/db/postgres/patches/023-add-unique-constraint-on-table-x_user.sql

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--
--     http://www.apache.org/licenses/LICENSE-2.0
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select 'delimiter start';
CREATE OR REPLACE FUNCTION create_unique_constraint_on_username() 
RETURNS void AS $$
DECLARE
 v_attnum integer := 0;
BEGIN
 select attnum into v_attnum from pg_attribute where attrelid in(select oid from pg_class where relname='x_user') and attname='user_name';
 IF v_attnum > 0 THEN
 	IF not exists (select * from pg_constraint where conrelid in(select oid from pg_class where relname='x_user') and conname='x_user_uk_user_name' and contype='u') THEN
 		IF not exists (select * from pg_index where indrelid in(select oid from pg_class where relname='x_user') and indkey[0]=v_attnum) THEN
			ALTER TABLE x_user ALTER COLUMN user_name TYPE VARCHAR(767),ADD CONSTRAINT x_user_UK_user_name UNIQUE(user_name);
 		END IF;
 	END IF;
 END IF;
END;
$$ LANGUAGE plpgsql;
select create_unique_constraint_on_username();
select 'delimiter end';